2001 S430 Transmission Repair
 

Hello all!

Well I have read through this site and have come across numerous DIY's to the repair of the "transmission stuck in limp mode". My poor baby has been sitting for over a month in my garage due to this reason and I have made my mind up to repair it myself. I have gone through all the socket cleaning routines and have had no luck.

I am mechanicly inclined (complete engine overhaul of a grey market 1986 190 2.3-16 with great success). My experience with automatic transmissions is limited but need to dive in head first.
I do not have a scanner but I will get one soon but all of my problems seem to point to the conductor plate so that is what I am about to change. My car is a 2001 S430 sport with 150 000 miles and the is no indication of excesive wear on the plates and no slipage. The gear changes were always smooth but the car would go into limp mode every now and then and stay in the last good gear. It would reset after switching of the ignition. Now it is in second and will not come out. Checked for leaks and found a little oil in the 13 pin socket (not excesive but a little wet). Replaced the o-ring and cleaned it out but still stuck in second.

Before I start this process I have a few questions to the members of this forum.

How many miles do you member think I have left on this tranny? Is it worth the effort of replacing the conductor plate only to have the tranny fail in say 10 000 miles? I can get a rebuilt 1 for 3K but am a little concerned for quality. Mercedes wants 7K plus. Hmmmm. I do not have the facility to drop the tranny here so what else do I do? She is a beautifull car and I would hate to let her stand here.

Any input would help.

I read on here that these transmissions can be had all day long rebuilt for $1,300 at many tranny shops.. obviously you will have to put it in, but that shouldn't be too hard.. I have been told these trannys are very sturdy.. I see ML430's which are all 4matic with 200k+ miles and running strong so I would think if your tranny hasn't been nuetral dropped and picked on in general it should be okay.. but you will never know for sure.. How hard is a conductor plate swap? I thought it was fairly easy.. it only takes ten minutes to replace the switch, but sounds like you have already taken care of that part..

Yea, done that. Need to get a scan tool, any sugestions?

My tranny on my s430 lasted till 185k miles
I got a used one from a forum member for $500 with 80k miles and my mechanic installed it for $300

That was a good Deal! Got to keep my eyes open for that. Thanks

Limp mode
 

My 2001 s430 transmission is stuck in limp mode. I changed trans oil, filter, gasket, conductor plate,13pin plug o rings, and also cleaned tcm. These were procedures I have learned from the forum to geg it out of limp mode. Nothing worked so far. The only thing I havent checked yet is the speed sensors. Since all other possibilities have been eliminated, should I focus on the sensors now?

The tcm was full of fluid and there was a blown capacitor on the the board. I even replaced the capacitor and double checked the connections on the board. The wires are definitely contaminated and I will try to address that before i buy new sensors. I heard of one guy who used cimpressed air through the 13pin connector and pushed enough fluid out that his limp mode was corrected. I will update you guys on my progress.
2 other issues, radiator fan is dead and headlight switch does nothing when I turn it on. Any thoughts?

Once I change the tcm will I have to hook it up to a STAR scanner and have it programed? Also I was told that once I remove the 13pin plug with the battery still connected it automatically sends the car into limp mode bc of the code it throws when the plug is disconnected from the trans and I have to have the codes cleared with the proper scanner to get it out of limp mode. Is this true?

I did fluid change on mine and replaced the connector plug without any issues. Has anybody ever spilled liquid on your shifter?